Hi,

I want to build a nanovolt signal condition circuit so I select LT1028 as my LNA by reading some literature. Then I star to build a circuit like the picture.
Although it run in Multisim , the actual circuit I built on the plug-in breadboard can't work . Then I use a multimeter to test every node so I find only negetive side supply working. Is the circuit right ?

Or could you teach me how to build a qualified circuit ? I used to do it referring the circuit in the datasheet but my circuit always went wrong ,which made me doubt whether I took the wrong approach.

 

hi waa,
Welcome to AAC.
This is your circuit in LTSpice, without the 47pF, the sim is unstable and oscillates around 900kHz.
Please post a clear photo image of your actual project.

E

 

Hi teacher,
Here are my circuit, and when I connect the supply and turn on it , the source turn off . I don't know how to build the circuit now . So I need your help . Thanks.

 

hi W,
A quick look, it shows that pin #4 of the OPA is connected to +Volts of the PSU. please check.
E

 

hi W.
Please confirm that I have marked the wiring correctly.
E

 

I try to use different color wire from the power supply, it helps to keep that straight. Looks like you’ve got ground from the power supply connected. Most power supplies that is chassis ground and I’ve had issues with that being used, it’s noisy and sometimes creates shorts from the dual supply. It should have positive from one connected to negative from another to create a virtual ground from the power supply. Please review the power supply.

 

Sorry for my afk and the wrong connection . Now I have reconnected it .

I found my supply still down to 2.3V. I thinik there are some mistake I ignored.

 

Remove all the ground connections from your power supply the ones on the green screw terminal. You’re shorting it out. You should only have 4 wires two of which are on the virtual ground between the two supplies

 

Hi teacher ,
First, is the virtual ground that the green screw terminal don't connect anything?
Today I had rebuild my circuit . And I found I still meet these problem. Here is my new circuit .

I input a sine signal of 6Hz, 10V and the image of the oscilloscope is here which is similar to the image of turnning off the power.

I had spent all day in these problem but I couldn't solve it .

 

Could you draw a schematic of how you wired this up including all compoent values? It’s hard to follow the same color wires and two breadboards.